The range of services offered by wireless communication networks continues its evolution from essentially voice-only service to a rich combination of data services in addition to voice service. One consequence of this evolution is that large portions of the wireless communication network are increasingly designed with an emphasis on supporting the newer, higher bandwidth data services. Wireless Internet access in support of web browsing and streaming media services are examples of these higher bandwidth data services.
In keeping with the nature of these newer data services, the wireless communication network is increasingly packet oriented. For example, a wireless communication network may be, at its core, an assemblage of various network entities interconnected through a packet-based network. While this arrangement suits the packet data flowing between the communication network and the Internet or other packet data networks, it sometimes poses special challenges for legacy services, such as voice.
For example, to reduce the amount of data carried internally by the communication network, voice encoding and decoding (vocoding) functions may be transferred from the radio access network (RAN) to a gateway device, such as a media gateway, that connects the RAN to the Public Switched Telephone Network (PSTN). Voice data received from the PSTN at the gateway device for mobile stations supported by the RAN is compressed and formatted into voice frames, which are then transferred to the RAN in packetized form via some type of packet network interconnecting the RAN and the gateway device.
Locating vocoding functions remote from the RAN imposes special challenges when the RAN needs to assert vocoding control in support of signaling operations. For example, one approach to transferring signaling information to a mobile station is referred to as dim-and-burst, and involves applying greater compression to the voice data so that a voice frame has “room” for one or more signaling bits. Thus, a number of rate-constrained voice frames may be used to transmit a signaling message from the RAN to the mobile station, but only if the RAN has some mechanism for generating or at least requesting the generation of such rate-constrained frames.
Controlling the vocoder in support of dim-and-burst signaling is straightforward when the RAN performs vocoding, but is more complicated when a remote network entity performs the vocoding. When vocoding is remote from the RAN, the network, must have a reliable mechanism for remote vocoder control.